Even more flummoxing is Biden's actual record. Put aside the fact that Biden's biggest backers are trial lawyers and credit card company lobbyists (so much for attacking business-as-usual), and there's the signature issue of Obama's campaign: the Illinois senator's superior judgment on the war in Iraq. In his months-long battle against Sen. Hillary Clinton, Obama insisted that his early opposition to the war represented singular proof of his qualifications to be president. But Biden, with his "unparalleled foreign policy experience" in the words of an Obama senior advisor, supported the 2003 invasion of Iraq on the same grounds that Clinton did.

So Obama asks voters to value judgment over experience or expertise; but when Obama himself chose someone best qualified to be president in his stead - "above all, I searched for a leader who is ready to step in and be president" he proclaimed Saturday in Springfield, Ill. - he went the opposite way.

Perhaps that explains why Obama accidentally introduced his VP as "the next president of the United States."

Of course, we know why Obama really made this choice. He thinks Biden will help with Pennsylvanians, Catholics, men and the working class. And Biden is ready to serve as the kind of partisan attack dog that Obama, until recently, decried as an unhealthy feature of our politics.

That's fine. Except it suggests that so much of Obama's new politics has been just words after all. And with Biden onboard, we know words are one thing the Democratic ticket will never run out of.